Nearly half of all crown courts across England and Wales were left empty on Monday, a survey suggests, even though lawyers say they have never known the backlog of criminal cases to be so bad.

Law experts suggested Ministry of Justice cuts to the number of sitting days and recorders – junior, part-time judges – were to blame for the large number of courtrooms being left unused.

Although there is usually a seasonal dip in trials during the summer, the extent of the underuse prompted warnings about delays to justice from the two main legal professional bodies – the Bar Council and the Law Society.

The survey, coordinated by Jonathan Dunne, a Nottingham-based criminal barrister at KCH Garden Square chambers, found that 127 courtrooms out of 260 were sitting idle. In Leicester, for example, four out of six courts were empty. In Snaresbrook, east London, 11 out of 20 were silent.

His research, conducted with other barristers around the country, covered 34 crown court centres – around half of the criminal justice estate.

“There are thousands of cases backed up, relisted and delayed,” Dunne said. “Judges are perfectly open with us: they have had their sitting day allocations cut. In my area there are 500 trials they want to do.”

He said cases involving defendants in custody were being given priority because there were rules preventing them from being held on remand for longer than six months. This had resulted in trials for defendants on bail being scheduled for next summer, he said.

“Listing times are running further and further ahead. I have never known it this bad,” he said. “It’s an easy soundbite to promise to hire extra police officers and create more prison places, but the bit in the middle [the courtroom trial] is crying out for more money.”

He said only two courts were operating to full capacity on Monday, Southampton and Chester, where recorders were being used to hear cases.

Since 2010, 295 courts across England and Wales have closed under an MoJ austerity drive, including half of all magistrates courts. The Criminal Bar Association has complained that recorders are effectively being employed on zero-hours contracts as their sitting allocations are slashed.

Richard Atkins QC, the chair of the Bar Council, which represents barristers, said: “That so many crown courts are sitting empty will come as a devastating blow to those victims of crime who are waiting for their cases to come to court or who are waiting for justice to be done to those who have admitted committing crimes against them.

“Whilst I am encouraged by the news that the government intends to increase the number of serving police officers, funding must be provided to ensure that those who are alleged to have committed crimes can be placed before a functioning court without delay. Justice delayed is justice denied.”

David Greene, the vice-president of the Law Society, which represents solicitors, said: “We are aware that many cases are taking longer to reach court, in part because thousands of suspects are now released under investigation. With no fixed time limit, cases can take months or even years to go to court.

“There are concerns that in some regions HM Courts & Tribunals Service (HMCTS) appears to be directing work from some courts towards others. This has led to many courts standing idle while others are overbooked. HMCTS has also reduced the number of days it will pay for sitting judges.”

An HMCTS spokesperson said: “There is no shortage of judges in the crown court and sitting day requirements and waiting times are reviewed throughout the year, with additional recorders deployed according to demand. Last year saw a 12% reduction in crown court trial cases and the allocation of sitting days reflects this. Waiting times for these cases are the shortest since 2014.”